Rheostat



Nov. 9 1926. 1,606,153

H. A. DOUGLAS RHEOSTAT Filed Jan. 7, 1926 Patented Nov. 9, 1926.

UNlTED. STATES HAIB'RY A. DOUGLAS, OF BROMSON, MICHIGAN.

# RHEOSTAT.

Application filed January 27, 1926. Serial My invention relates toelectrical apparatus employing a spirally coiled wire wlnding and acontacting wiper engaging the wire of such winding for varying theampere turns thereof. The device of my invention is useful in connectionwith rheostats having spiral windings or in connectionwith otherelectrical apparatus having spiral windings. My invention, in itspreferred embodiment, is an improvement upon the structure disclosed inmy United States Patent No. 1,438,753, dated December 12,

1922. The device of my present invention includes an improvedconstruction. of the wiper and the provision of improved operatingmechanism which preferably includes no parts that are projected to varyng extents beyond the winding, 1n eifeotlng adjustment.

My invention, in accordance with one of its characteristics, includestwo relatively rotatable members provided with portions in threadedengagement, one of said members including a spirally coiled wire windingand the other including a wiper engaging'said winding, and a guideengaging one of the aforesaid member portions to force relative turningmovement of said two member portions and along which guide the memberportion engaged thereby moves during such relative turning movement. Inthe preferred embodiment of the invention the threading of said engagedmember portions and the spiral of the coiled wire are of the same pitch.The wiper is desirably surrounded by and engaged with the interior ofthe wire winding. This wiper 1s preferably in the form of an outwardlyspring pressed plunger projecting from a spring barrel carried by a nutwhich 1s threaded upon a post that is assembled with and surrounded bythe spiral winding and constituting a part of the winding member. 1 Theinvention will be more fully explained in connection with theaccompanying drawing in which Fig. 1 is a longitudinal sectional viewillustrating the preferred embodiment of the invention; Fig. 2 is asectional view on lii1e2-2 of Fig. 1; Fig.

3 is a perspective view of the guide shown in Figs. 1 and 2; and Fig. 4is a perspective view ofthenut and the wiping plunger carm ried thereby.

The wire 1 of the rheostat-or other wound electrical instrument isspirally disposed preferably upon the interior of a hollow drum 2. Thisdrum is cup-shaped and is mounted at its front and bottom end upon anysuitable support 3 by means of the attaching screws 4. A threaded post5is coaxial with and surrounded by the drum or cup and is fixed upon theclosure 6 for the rear end of the cup to be fixed with the winding 1' asis preferred, the post thus constituting a part of the winding member. Anut 7 is screwed upon said post. This nut is formed with a hollow radialextension 8 constituting a barrel which houses aspring 9. The wipingcontact is in the form of a metallic plunger 10 which is pressedoutwardly by the spring into engagement with A groove 11 is formed inthe contacting end of the plunger to receive and afford goodv contactwith the wire. A guiding sleeve12 encloses the threaded post 5 and thenut 7 This sleeve is formed [with a slot 13 extending along the same andthrough which the nut extension 8 passes. Said sleeveis provided with ashaft extension 14 which is journaled within the front end wall of thecup 2. This shaft projects forwardly beyond the cup and its mounting 3and has the knob or handle 15 secured to its front end by a set screw16. The knob is provided with the usual dial flange 17.

As the handle is turned, the shaft 14: and thesleeve 12 are turned. Onelongitudinal side or the other of the slot 13 engages the nut' extensionand forces the nut to turn upon the stationary post 5. As the nut thenut. The threading of the portion5 of the winding member and the spiralof this winding are of the same pitch so that the contacting end of thewiper 10 will follow the wire engaged thereby as the handle is turned.The handle 15 is confined to a fixed terminal binding screw 17 within athreaded bushing 18 which is connectedwith-one end of the winding 1, anda terminal'binding screw 19 within the reduced rear end of the metallicpost 5. As the parts 5, 7, 8, 9 and 10 are metallicv and in electricalconnection, the circuit wire clamped by the screw 19 is electricallyconnected with the wiper 10. The portion of the wire coil 1 betweentheselected point of contact thereof with the wiper and the screw 17 isthus included in circuit with the wiring that is connected with thescrews 17 and 19.

Changes'may be made without departing from'the invention.

Having thus described my invention, I claim:

1. The combination with two relatively rotatable members, one surroundedby the other and one being provided with portions in threadedengagement," one of said members including a spirally coiled wirewinding and the other including a wiper engag-' ing said winding; and aguide engaging one of the aforesaid member portions to force relativeturning movement of said two member portions and along which guide themember portion engaged thereby moves during such relative turningmovement, the threading of said en aged member portions and the spiral0% the coiled wire being of the same pitch.

-, 2. The combination with two relatively rotatable members providedwith portions 'ing and the other including a in threaded engagement, oneof said members including a spirally coiled wire winding and the otherincluding a wiper engaging said winding; and a guide in turning relationto one of said members and engaging'the said member portion of the othermember to force relative turning movement of saidv two member portionsand. along which guide the member portion engaged thereby moves *duringsuch relative turnmg movement, the threading of said engaged memberportions and the spiral oil the coiled wire being of the same itch.

3. The combination with two re atively rotatable members provided withportions in threaded engagement, one of said members including aspirally coiled wire windwiper sur rounded b and engaging the interiorof said winding; and a gulde engaging one of the aforesaid memberportions to force relative turning movement of said two member portionsand along which guide the member portion engaged thereby moves duringsuch relative turning movement, the .threading of said engaged memberportions and the spiral of the coiled wire being of the. same pitch.

4. The combination with two relatively rotatable members provided withportions in threaded engagement, one of said mem bers including aspirally coiled wire winding and the other including. a wipersurroundedby and engaging the interior of said winding; and a guide inturning relation to one of said members and engaging the said memberportion of the other member to torce relative turning movement of 5. Thecombination with two relatively rotatable members provided with portionsin threaded engagement, one of sald members including a spirally coiledwire winding and a threaded post surrounded by and extending along theaxis of said winding and the other member including a Wiper alsosurrounded by and engaging the interior of ,the wire winding, and a nutin threaded engagement with said post; and a guide also surrounded bysaid winding and in engagement with the nut to force relative turningmovement of the nut and post and along which the nut moves during suchrelative turning movement, the threading of the post and the spiral ofthe Winding being of the same pitch.

6. The combination with two relatively rotatable members provided withportions in threaded engagement, one of said members including aspirally coiled wire wind-' i ing and a threaded post surrounded by andextending along the axis of said winding and the other member includinga nut in threaded engagement with said post, a spring barrelconstituting a continuation of the nut, a spring within the springbarrel, and a wiper in the form of a plunger pressed by said springagainstthe interior of said winding; and a guide also surrounded bysaidwinding and in engagement with the nut to force relative turningmovement of the nut and post and along which the nut moves during suchrelative turning movement, the threading of the post and the spiral ofthe winding being of the same itch. 7. The combination of two relativelyrotatable members provided with portions in threaded engagement, one ofsaid members including a spirally coiled wire winding and a threadedpost surrounded by and extending along the axis of said winding and theother member including a wiper also surrounded by and engaging the interior of the wire winding, and a' nut in threaded engagement with said0st; and a guide also surrounded by said andin engagementwvith the nutto force relative turning movement of the nut and post and along whichthe nut moves during such relative turning movement.

8. The combination with two relatively rotatable members provided withportions in threaded engagement, one of said members including aspirally coiled wire winding and a threaded post surrounded by andextending along the axis of said winding Winding k and the other memberincluding a nut in threaded engagement with said. post, a spring barrelconstituting a continuation of the nut, a spring within the springbarrel, and a wiper in the form of a plunger pressed by saidspringagainst the interior of said Winding; and a guide also surroundedby said winding and in engagement with the nut to force relative turningmovement of the nut and post and along whichthe nut moves during suchrelative turning movement.

9. The combination with -two relativelyduring such relative turningmovement.

10. The combination with two relatively rotatable members, onesurrounded by the other and one being provided with portions in threadedengagement, one of said members including a spirally coiled wire windingand the other including a wiper engaging said winding; and a guide inturning relation to one of said members and engaging the said memberportion of the other member to force relative turning movement of saidtwomember portions and along which guide the member portion engagedthereby moves during such relative turning movement.

11. The combination with two relatively rotatable members provided withportions in threaded engagement, one of said members including aspirally coiled wire winding and the other including a Wiper surroundedby and engaging the interior of said winding; and a guide engaging oneof the aforesaid member portions to force relative turning movement ofsaid twomem ber portions and along which guide the member portionengaged thereby moves during such relative turning movement.

12. The combination Witlrtwo relatively rotatable members provided withportions in threaded engagement, one of said members including aspirally coiled wire winding and the other including a wiper surroundedby and enga ng the interior of said winding; and a gpide in turningrelation to oneof said members and engaging the said member portion ofthe other member to force relative turning movement of said two memberportions and along which guide the member portion engaged thereby movesduring such relative turning movement.

In witness whereof, I hereunto subscribe my name.

HARRY A. DOUGLAS.

